Regarding a mechanism for preventing entanglement of wire wound around a reel of a reinforcement binding machine, JP 11-104777 A, filed by the present applicant, discloses a “Brake Mechanism of Wire Reel for Reinforcing Bar Binding Machine”.
In this reinforcement binding machine, the rotation of the wire reel is braked substantially simultaneously with the completion of wire feeding, thereby preventing wire entanglement due to idle running of the reel.
FIG. 12 shows this reinforcement binding machine, in which a reel 2 around which a wire 3 is wound is retained at the rear of a reinforcement binding machine 1. The wire 3 drawn out of the reel 2 is fed to the front portion of the reinforcement binding machine 1 by a wire feeding means 5, and is curled as it is fed along a guide 6 having an arcuately extending groove to be formed into a loop around reinforcing bars 7 crossing each other in a cross-like form. The wire 3 wound around the reinforcing bars 7 in a loop-like form is grasped by a grasping portion 4, and then the wire feeding by the wire feeding means 5 stops; further, a twisting hook 8 having at its forward end a groove for holding the wire 3 in a loop-like form approaches the wire 3, which is inserted into the groove. Thereafter, the twisting hook 8 rotates to twist the wire 3 to thereby bind the reinforcing bars 7, and then the wire 3 is cut by a cutting means provided in the grasping portion 4, which then releases the wire 3.
FIG. 13 shows a brake mechanism for preventing idle running of the reel 2 of the reinforcement binding machine 1. A mounting shaft (not shown) retaining the reel 2 is provided in the reinforcement binding machine 1, and a gear 10 is attached to a side portion of the reel 2. Formed in the periphery of the gear 10 are engagement recesses 11 allowing rotation in one direction, and in the vicinity of the engagement recesses 11, there is arranged a brake claw 12 consisting of a latch claw. The brake claw 12 is supported by a base 13, which is rotatably supported by a shaft 14 provided on the binding machine main body 1. The base 13 is urged by a spring 15 such that the brake claw 12 is pressed against the gear 10, allowing the gear 10 to rotate counterclockwise as seen in the drawing and prohibiting clockwise rotation of the gear 10.
The above-described reinforcement binding machine 1 is of the type which, after feeding out the wire 3, allows rotation of the wire 3 in one direction only.
Recently, however, there is a demand for a reinforcement binding machine which, after feeding out the wire 3 and winding it around the reinforcing bars 7, pulls back the wire 3 from the reinforcing bar 7 side to thereby achieve a reduction in the consumption amount of the wire 3, and in the brake mechanism of the type described above, returning of the wire 3 cannot be effected.
Further, if, during forward feeding of the wire 3 toward the reinforcing bar 7 side or reverse feeding thereof from the reinforcing bar 7 side, the reel 2 makes idle running, there is a fear of the wire 3 loosened on the reel 2 being entangled.
The present invention has been made in view of the above problems. It is an object of the present invention to provide a construction in which, when the feeding force or tightening force for the wire is canceled and the tensile force for the wire is weakened, idle running of the reel is prevented to eliminate generation of wire entanglement on the reel while allowing the reel to rotate in both the normal and reverse directions.